The proposed research is designed to begin to evaluate the natural history of insulin dependent diabetes within a complete population of insulin-dependent diabetic cases who have been identified at onset of their disease. The focus is to follow up and survey the morbidity, mortality and socio-demographic characteristics of IDDM cases who are registered in the Allegheny County Registry (approximately 1,200 cases). The IDDM cases are individuals less than age 20 at diagnosis, diagnosed between 1965 and 1980, Allegheny County resident at time of diagnosis and discharged from the hospital on insulin. Approximately 60% of the registry has already been traced and the mortality status determined. They had originally been seen at Children's Hospital of Pittsburgh. A goal of the current research is to collect morbidity and mortality data on the additional 40% of the cases in the Allegheny registry who have not been seen in Children's Hospital as well as socio-demographic data. This will be one of the first natural history follow-up studies in a complete population which examines cases identified at diagnosis. The second goal will be to validate the causes of death for each person within the cohort who had died (approximately 180). The third goal will be to compare the adult diabetic cases with adult non-diabetic siblings in order to evaluate the relationship of diabetes and diabetes complications to socio-demographic variables including the likelihood of marriage, education attainment, children, occupation, social class, medical care usage and health habits. This research is an outgrowth of a natural history study and involves reduced expense because the cases in the cohort have been identical, many of the cases have been traced and the survey tools and methods are well tested.